They appear to be unrelated for now. But three of the attackers were recently arrived refugees. One was a German-Iranian dual citizen. And all were young men between the ages of 18 and 27.

Bavaria's Interior Minister, Joachim Herrman, was visibly shaken early Tuesday morning, hours after a Syrian refugee blew himself with a backpack explosive.

"I have been Interior Minister in Bavaria for nearly nine years," he told the press. "And I have never experienced anything like this until now."

Germany is on edge. "Wilkommenskultur" -- the buzzword that welcomed more than a million refugees into the country last year -- has given way to an unsettling fear that the country is not prepared for the security and integration challenges of taking in a diverse, often traumatized population that comes with their own emotional baggage.

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Police are still piecing together how and why Mohammad Daleel, a 27-year old Syrian refugee living in Ansbach, decided to pack a bag of explosives, screws and bolts and detonate it outside a crowded music festival.

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On his phone, police found a video of a masked man they believe to be Daleel swearing allegiance to ISIS leader Abu Bakr al-Baghdadi, threatening to carry out attacks on Germans.

Investigators say Daleel had also received psychiatric treatment for attempting suicide twice. Two weeks ago, Daleel received a notice that he was due to be deported to Bulgaria, his first point of entry into the EU.

But Daleel's refugee neighbors never saw any signs of extremism, or even depression. Outside the Hotel Christl, a rundown hotel converted into shared refugee accommodation, Mahmood Mubariz, a refugee from Pakistan, told me that he had seen a smiling Daleel only a week ago waving from his balcony.

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"He was always happy," Mubariz said. "He never complained about Germany. He told me that he left his country because of the civil war in Syria. If he was an extremist, why didn't he join those groups in his homeland? Why come here?"

Mubariz was shocked to learn that Daleel had attempted suicide and told me that his neighbor had been trying to land a job at the local McDonald's. Now Mubariz fears a backlash against refugees.

"This will create so many problems for us. There are so many people in Germany who loved us and respected us. And what has he done? Killing their children and destroying their rules? It's not fair. We must respect their country."

Far right tries to capitalize

Across the street, an elderly couple stepped out of their homes to watch the police before heading to the market.

"Most of the refugees have been so friendly to us. It doesn't change our opinion on welcoming refugees," the wife told me. "But we also can't see what's going on in their minds. This is just so shocking. And that scares us."

"Angst," the Germany word for fear, is now commonly heard during conversations in local beer gardens. Far right groups have tried to capitalize on that public fear, ramping up their anti-immigration rhetoric.

On Tuesday evening in the medieval town square of Ansbach, police fenced off a small far right protest. Demonstrators held up banners that read "Foreigners Out!" and "Stop the Asylum Flood!" as a loudspeaker droned on about the dangers of immigration. A few feet away, a rowdy crowd of opposing protesters shouted back "Nazi Pigs!" and "Nazis Out!"

'We can't let them frighten us'

Claudia Frosch has more reason to be scared than most in Ansbach: She was sitting at the same table as Daleel just before he detonated. She noticed him because he was wearing earphones, but they weren't plugged into the mobile phone that he was constantly checking.

"He was a good looking young man, quiet. Well dressed," she told me. "I didn't think he was a foreigner. I thought he was German, a local."

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She came away from the attack unscathed, but her friend was hospitalized after a metal bolt from the explosion ripped through her neck.

"I'm scared. My hands still shake." she said. "I just can't believe something like this would happen here."

And yet Frosch was one of many local residents that returned to the crime scene after police lifted the cordons. Within hours, the café and restaurant next door had reopened, and Bavarians were enjoying an evening beer right next to the shattered glass, the blood stains and the chalk outline of the attacker's body on the cobblestones.

"Why not?" said one local resident with a glass of beer in hand. "We can't let them frighten us. We must get back to our normal lives."